When a peripheral device with a bus protocol different from the bus protocol of an internal local bus is connected, a protocol conversion circuit is provided and communication is established between the different protocols. When data of a low-speed peripheral device is read from a high-speed local bus, because the protocols are different, the peripheral device divides transfer data and transfers the divided data, however, outputs the divided data to the local bus as one piece of transfer data. Moreover, there is a case where the divided data is transferred in random order, and therefore, the divided data is rearranged.
A general buffer circuit that rearranges transfer data as described above has a capacity large in size compared to the maximum total amount of transfer data and the capacity is not used effectively.
Further, when rearrangement is implemented, latency in the output to the local bus becomes high.